1. Field of the Invention
The present invention relates generally to data communications networks and, more specifically, the present invention relates to virtual local area networks.
2. Background Information
A Local Area Network (LAN) has generally been defined as a network of computers or workstations located within a single broadcast domain. Computers that are connected to the LAN can become connected for the interchange of data. Once a message transmitted to the LAN, the message is broadcast to and received by every other user connected to the LAN.
Virtual LANs (VLANs) are used to segment networks into logically defined virtual workgroups. By logically separating the segments, messages are generally broadcast only to the workstations in the logical segment. As a result, the overall traffic is reduced since traffic remains within the segment. In addition, an added level of security is realized with VLANs since workstation users no longer receive broadcasts addressed to other segments.
There are varieties of known methods to identify and route data between workstations in a VLAN. One method is explicit tagging, which involves a VLAN tag being added to an ordinary data packet or frame. The VLAN tag indicates, among other things, the VLAN to which the data frame belongs. Another method of identifying and routing data between workstations in a VLAN is implicit tagging. Implicit tagging methods include associating a particular set of ports to a particular VLAN or associating particular communications protocol to a particular VLAN.
In some instances, some of the workstations that are connected to the VLAN may be "VLAN aware." These workstations recognize the VLAN tags that are added to the ordinary data frames. In other instances, the workstations that are connected to the VLAN are "non-VLAN aware." These workstations do not recognize the VLAN tags that are added to the data frames.
What is desired is a method and an apparatus providing data communications in networks such as VLANs. Such a method and apparatus should have the ability to transfer tagged and untagged data frames among VLAN aware and non-VLAN unaware workstations. Such a method and apparatus should convert the data frames as appropriate to enable compatibility with both the VLAN aware and non-VLAN unaware workstations. In addition, error correction codes in the frames should be maintained accordingly.